A metal disc with a hole in the middle. There are several different types of washers used on bicycles, to serve different purposes:

Flat washers are commonly used between nuts or bolt heads and the parts that they tighten against. For most fasteners, it is desirable that the part that is turned by the wrench or screwdriver have a washer under it to protect the surface from the turning fastener. Flat washers are also commonly used to spread out the load when a fastener is attached to a thin or fragile part.

Spacer washers are flat washers of various thicknesses just designed to take up space on a threaded shaft.

Lock washers have one or more directional teeth that act like pawls against the bearing surface of the fastener. These make it easier to turn the fastener in the tightening direction than in the loosening direction, so it is less likely that the nut or bolt will rattle loose.

Serrated washers have teeth on one side. These are typically used on nutted hubs, with the washer between the axle nut and the forkend. The smooth side faces the nut, and allows the nut to turn without rubbing against the teeth. The serrated (toothy) side bites into the forkend to help keep the axle from slipping forward due to chain tension.

Keyed washers usually have a tab poking into the hole, and fit over a threaded shaft that has a groove ("keyway") for the tab to slide through. Keyed washers are commonly used between a threaded bearing race, either cup or cone, and its locknut. The intent is that when you tighten the locknut, it presses the keyed washer against the threaded bearing race but does not cause the bearing race to turn on its threads, so it stays in adjustment.

Keyed washers are almost always used on threaded headsets, often also used on the bearings of pedals.

Formerly, keyed washers were used on hub axles, but that has gone out of favor.

Anti-rotation washers have a non-round hole and fit on a matching non-round shaft. These washers are designed to keep parts from rotating.

Internal gear hubs often have combination serrated/anti-rotation washers. These feature a tab or tabs that fit into the forkend'saxle slot. They are used to keep the hub'saxle from twisting in the frame. (Internal gear hubs have one or more gears mounted on the axle inside the hub, and this gear has to resist some force from pedaling in the higher or lowergears . The force is in opposite directions, depending on the gear selected, so if the axle in not properly secured, it will twist back and forth, causing the axlenuts to loosen up.

Radiused washers are used for mounting caliper brakes to frames/forks. They are flat on one side, the side that the brake caliper is on. They are curved ("radiused") on the opposite side to match the curvature of the brake bridge or fork crown.

Wedge bolt

Conventional handlebar stems use a long bolt running down the middle of the shaft to clamp the stem to the inside of the steerer. At the bottom of the stem shaft, this bolt screws into a special shaped nut. These nuts are of two different types:

Wedge-type stems have the bottom of the shaft cut off at an angle, and the nut is cylindrical with an angled top surface to match the angle of the bottom of the stem shaft. As the bolt is tightened, the wedge-shaped nut is pulled sideways so that it presses against one side of the steerer, and the shaft presses against the other side of the steerer. Most newer stems are of this type.

Expander-type stems have square-cut shaft bottoms, but have one or two slots cut up from the bottom of the shaft. The nut is in the shape of a truncated cone. As the bolt is tightened, the conical nut spreads the bottom edge of the stem shaft outward, pressing it against the inside of the steerer.

Each system has advantages and disadvantages:

Wedge-type stems:

Provide a more positive lock against the steerer (which may be an advantage or a disadvantage...if the stem is too tight there is a greater risk of bending the handlebars in a crash.)

Are easier to adjust. In most cases, just loosening the wedge bolt will permit the bars to be raised, lowered or straightened.

Are cheaper to manufacture.

Expander-type stems:

Are less likely to damage the steerer if overtightened.

Do not require quite as deep an insertion into the steerer.

Are harder to adjust, because it is usually necessary to knock the wedge loose by striking it with a mallet after loosening up the bolt.

Note:Steerers are butted at the bottom, so the hole in the steerer is constant-diameter until near the bottom, then the walls taper inward in the butted section.

It is vitally important that the stem extender (or stem) not be inserted so far that the wedge is installed where the steerer is narrowing, or it could come loose unpredictably.

When this happens, only the edge/corner of the quill or wedge contacts the steerer, and it is trying to "grab" a slanted surface.

This is sometimes a problem on smaller frames if you try to insert the stem or a stem riser too far down into the steerer.

Disparaging term used by recumbent fans to describe a conventional upright bicycle.

Weight weenie

Disparaging term used to describe cyclists who reduce the weight of their bicycles by using lightweight and modified parts, often at the expense of utility and reliability. In the 1970s, it was common for weight weenies to drill holes in bicycle components ("drill them out"). The ultimate weight-weenie component is the drilled-out water bottle.

Weinmann

A noted manufacturer of rims and (formerly) brakes. Formerly, Weinmann was based in Belgium and Switzerland, but the current Weinmann company is U.S. based.

Welding

A process of joining similar metals by heating them so that they melt into one another. Compare to brazing.

Well

The deepest part of a rim between the flanges. To remove or replace the tire, it must be dropped into the well on one side, so the opposite side can be lifted over one of the flanges.

A colloquial name for Raleigh pattern rims. "Westrick" is a made-up word combining "Westwood" with "Endrick." Westwood rims were only for use with rod brakes; Endrick rims were only for use with caliper brakes, but Raleigh Pattern, a.k.a. "Westrick" rims can be used with either type.

They combine the raised (or dropped, depending how you look at it) center that keeps rod brake shoes free from the risk of hitting the spokes, with the flat sides required for rim brakes.

One excellent feature of Westrick rims is their parallel sidewalls, which allow a caliper brake to work more evenly if a rim is out of true. However, the hollow, steel sidewalls are easily deformed by curb and pothole impacts, and the chromed steel braking surfaces are very slippery when wet.

The old-fashioned type of rim usually seen on roadsters. Westwood rims have rounded sides, so they are not suitable for use with caliper brakes. They are designed to be used on bikes with rod brakes, where the brake shoes rub on the inside circumference of the rim. The Westwood profile has a ridge between the braking surfaces. The spoke holes are drilled into this ridge, and the ridge protects against the brake shoes hitting the nipples.

Westwood rims are most commonly seen in the 635 mm (28 x 1 1/2) size, but they were made in most of the middleweight British sizes.

The distance from the center of the front wheel to the center of the rear wheel. In general, a bicycle with a longer wheelbase is more stable and comfortable; one with a shorter wheel base tends to be more manuverable. See: angles.

A device which keeps the front wheel of a bicycle from coming out of the fork if the axle nuts or quick release is loose. With axle nuts, the retention device is usually a washer under each axle nut, with a tab at one side that runs parallel to the axle and fits into a hole in the forkend. With a quick release, there have been three common types of retention device: the so-called "lawyer lips" on the forkend; tabbed washers like those used with axle nuts; or a pair of clips that pivot around special hub locknuts and attache to a peg on each fork blade. Only the clip type, invented by Schwinn engineer Frank Brilando and only used on Schwinn bicycles, prevents the wheel from coming off it the quick-release skewer breaks, and holds it securely enough that it can not wobble.

Wheel Sucker

A cyclist who drafts other cyclists without taking his or her share of pulling.

Wheelie

A wheelie (short for "wheelstand") is the act of using a combination of pedal thrust and weight shifting to raise the front wheel into the air. A skillful freestyler can lift the front wheel high enough that the center of gravity moves over the rear wheel, then ride the bicycle as if it were a unicycle. The correct verb to describe the act of doing a wheelie is "pop". Wheelies often cause great stress on a bicycle's fork when the front wheel comes back down.

A "nose wheelie" results when the front brake is applied hard enough to cause the rear wheel to lift off.
A controlled one is called a "stoppie" or "front wheelie." An uncontrolled one in which the cyclist goes over the handlebars is called an "endo" and may result in a "face plant."

Wheelie Bike

Also known as a "high-riser", "Stingray", "polo bike", "banana bike", "Chopper". The most horrible children's bikes ever made. Some who had them as children retain a sentimental attachment to them, so there is an active market in "collectible" wheelie bikes, but they were, in my considered opinion, an unmitigated disaster.

Early wheelie bikes were home-made by adapting a bike made for a small child for use by a larger child. A frame from a 20" wheel child's bike would be equipped with tall "ape hanger" handlebars and a "banana seat" which extended back over the rear wheel. The resulting weight distribution created a bicycle that would do a wheelie with the slightest effort.

The American bicycle industry, led by Schwinn with its "Stingray" and "Krate" models, jumped on this early '60's fad. Schwinn made a lot of short-term profit, but, I believe, the wheelie bike led to a serious long-term setback for the American bicycle industry.

Before the wheelie-bike craze, there was a well-established progression of frame sizes for growing children, from 16", to 20", to 24" and finally to 26" wheel bicycles. The wheelie bike killed the 24" bike market, because these bikes would sort-of fit children who should really have been riding on 24" wheels.

Wheelie bikes also greatly reinforced the idea that the bicycle was a child's toy, not a serious vehicle. Wheelie bikes were easy to do wheelies on, but their awkward riding position made them hellishly uncomfortable to actually ride more than a half-mile at a time.

Wheelie bikes in turn were killed by BMX bicycles, which are much more "rideable", but the 24" market never completely recovered.

Whitworth

Sir Joseph Whitworth was one of the great inventors of the 19th century. He invented the milling machine, and was the first to manufacture all-metal machine tools. I believe that he was also connected with the Rudge bicycle company (later acquired by Raleigh).

He was also one of the first to establish a standardized set of screw threads and wrench sizes. Whitworth fasteners were used in British industry up until the late 1960's, when Britain adopted the metric system. The Whitworth system is now virtually extinct.

Whitworth fasteners used a 55 degree thread angle. The wrench sizes were confusingly marked, the wrenches are all larger than you would think. This is because the dimension given on a Whitworth wrench is the diameter of the bolt thread usual for that size wrench, rather than the size of the head. Some Whitworth wrenches even have two marked sizes, because the same head size is used with one coarse thread and a different-diameter fine thread.

Some of the smaller-sized Whitworth threads are interchangeable with S.A.E. threads.

Wishbone

Wishbone type frames have seatstays that do not run all the way up to the seat cluster. Instead, there is a single tube running from the seat cluster down to where the brake bridge would normally be. The seat stays come up and join this tube, much as the blades of a unicrown fork join the steerer. The advantage usually given for this type of construction is that it provides a more solid mounting for cantilever brake studs, since there is only a short length of narrow seatstay above the stud.

Wooden rims

In many ways, wood is an ideal material for bicycle rims, and most bicycles in the early part of the century were equipped with them. They are light, strong, and resilient. Wood rims are not suitable for "clincher" tires, but worked well for other types.

Wooden rims went out of style for road bicycles when rim brakes came in, but continued to be use on the track well into the '40's. They were eventually outlawed for competition because of their dangerous failure mode: When a highly-tensioned racing wheel with a metal rim was damaged, it would fold up, but it would stay together. Similar wood-rim wheels, when overstressed, would suddenly turn into a cloud of sharp, dangerous splinters.

A type of valve very rarely seen in the U.S., which has a bottom similar to a Schrader and necks down to about the size of a Presta is the Woods valve, also known as the "Dunlop" valve. Woods valves were formerly popular in the British Isles and Asia. You can pump them up with a Presta pump.

Older versions work with rubber tubing and spit. If they don't hold air, you can unscrew the knurled ring that holds the valve core (the "Presta-sized" part) in place. You should see a short length of rubber tubing covering the inner part of the core. If the rubber tubing has deteriorated,, the valve won't work. Some patch kits include short lengths of replacement rubber tubing for this purpose. When installing new tubing, lubricate the valve core with spit before slipping the tubing in place.

Newer versions use a modern spring-loaded valve mechanism.

Wrench

A tool for turning nuts or bolts. This term is not common in British usage, where the term "spanner" or "key" is generally preferred.

Wrenches are divided into two families:

Fixed Wrenches are made of a single piece of metal, and only fit specific sizes of fasteners. Fixed wrenches are made for different sizing systems, including Metric, S.A.E., and Whitworth. Types of fixed wrenches include:

Box wrenches, which have a complete loop that surrounds the fastener. They are substantially stronger than open-end wrenches, and are the best to use for high torque applications, both because the wrench is stronger, and because it can contact more than two corners of the fastener.

Combination wrenches are double-ended wrenches with an open end and a box end, usually for the same size on each end. This is the most useful and most common general-purpose wrench style.

Open-end Wrenches have ends shaped like a two-tined fork. They normally have two parallel surfaces which bear against two of the sides of a fastener. Open-end wrenches are faster to put on to fasteners, and are the only kind that can be used where there is not clearance to slip a box wrench over the end of the fastener.(cone wrenches, headset wrenches, pedal wrenches and spoke wrenches)

Spoke wrenches have taller contact areas than most wrenches and have short handles for use in the close quarters between spokes.

Socket Wrenches, similar to box wrenches, surround the fastener. Unlike with box wrenches, the outside of the head of a socket wrench is circular so that it can reach a fastener which is recessed into a small hole. A socket wrench may have an offset handle, as with a peanut-butter wrench, but more often, the handle will attach to one end of the socket.

Most socket wrenches are part of modular systems, and have interchangeable handles available, including ratchet handles, torque-wrench handles, extensions, breaker bars, and screwdriver-type handles; also extensions, to insert the socket deep into a mechanism, and universal joints, to use when the socket can not be at a right angle to the handle. Extensions and universal joints are not commonly needed for bicycle work.

6 Point vs 12 Point: Socket and box wrenches for hex fasteners come in two types, 6 point and 12 point.

12 point is good for box wrenches, because it gives you twice as many possible orientations to put the wrench on the fastener. This is especially good for working in close quarters, but is rarely an issue on bicycles. 6-point wrenches are stronger and less likely to slip. Generally, 6 points are preferable for bicycle work when you have a choice.

A crank bolt wrench is a special socket wrench used to tighten and loosen the bolts or nuts which attach square-tapered cranks to axles. A crank bolt wrench may also include an Allen wrench, as some crank bolts use one. Some older cranks use different sizes: see my article on cotterless cranks.

Nutdrivers are smaller-sized socket wrenches with screwdriver-type handles. These are often faster to use than conventional wrenches, and the screwdriver-type handle makes it unlikely that you'll strip the threads of a smaller nut or bolt. 8 mm, 9 mm and 10 mm nutdrivers are among my favorite bike tools. They usually have a hollow handle so they can even be used to run a nut down a long bolt.

Y wrenches are socket wrenches shaped like a Y with a socket on the end of each arm. The common Y wrench for bicycle use has 8, 9 and 10 mm sockets to fit the nuts and bolts used on many brakes and derailers. It is a useful tool to carry for on-road repairs.

Hook spanners have an end shaped a bit like a capital "G". They wrap around a round fastener and the tail of the "G" fits into one of several notches on the fastener. Hook spanners are commonly used on bottom-bracketlockrings and track hub lockrings. They are also used on some headsets.

Allen Wrenches are hexagonal wrenches that fit into matching hexagonal holes. Only a few metric sizes of Allen wrenches are commonly used on bicycles. Many modern bicycles use only Allen-wrench fittings, reducing the weight of a bicyclist's tool kit substantially.

Spline Wrenches (including Torx, freewheel, etc.) have protruding splines on the inside or outside. Spline wrenches used on bicycles are mostly special wrenches which fit only one particular type or brand of bicycle parts. Many, including the one shown, need to use another wrench as a handle.

Adjustable Wrenches can be adjusted to fit different sized fasteners, usually by the use of a thumbscrew. They don't fit as well as the correct size fixed wrench, so good, well equipped mechanics only use them as a last resort.

Crescent ® Type Wrenches. Although "Crescent" is a trademark, it is commonly used in the U.S. to refer to a normal, angled head adjustable wrench regardless of brand. The jaws are set at a 30 degree angle to the handle to allow them to be used in tight quarters. They still are much bulkier than box wrenches or open-end wrenches.

Monkey Wrenches have their jaws perpendicular to the handle. They commonly open up much wider than crescent-type wrenches.

Pipe Wrenches are similar to monkey wrenches, except that they have serrated jaws, which are designed with a bit of play which causes them to grip more tightly when turned in the appropriate direction. Pipe wrenches are primarily used for plumbing, and generally have no bicycle application.

Adjustable pin spanners fit a range of different pin spacings. The spring-loaded Park SPA-1 (green) adjustable pin wrench is the most useful one for most adjustable bottom-bracket cups.

Wrenches are sometimes confused with pliers, and naive users sometimes try to use pliers for jobs that really require a wrench, usually resulting in damage to the nut or bolt so abused. It can also cause failure due to undertightening the part involved.